This week, as the nation prepares to observe the 10th anniversary of 9/11, Roll Call looks back at how Capitol Hill responded to the attacks and how that day's events changed — and didn't change — life in Washington.

Many of the Capitol Police officers who weren't stationed on the Hill on Sept. 11, 2001, were in training, preparing for an upcoming rating and certification evaluation and the impending International Monetary Fund demonstrations.

Officer Amy Thompson was at Anacostia Park, taking a break from civil disturbance training, when she saw the attack on the World Trade Center on television.

"One of our officials came and told us we needed to get back to the Hill and to jump in whoever's car you get to first and head back," she said.

Thompson arrived back at the Capitol and was put to work directing traffic. It was unlike any traffic work she had done before — all five lanes on North Capitol Street were heading out of the city, and no one was honking or asking for directions; they all just wanted out.

She remembers the eerie absence of taxis and buses on the street, another implication that something was wrong.

"I remember it going a lot easier than I thought it was going to be," she said. "I think people were so scared [that] they just wanted you to tell them anything."

Even though she wasn't sure what was going on, Thompson continued to direct people, offering them as much information as she could when asked by panicked passers-by.

"They teach us to have a certain level of command presence, and so no matter if you were in uniform or out of uniform, you have to come off like you know what you're doing," she said.

Thompson spent much of the rest of the day as a traffic officer, but many of the officers called back to the Capitol didn't have as much to do that day. Police officers knew they were needed, but with all the uncertainty, they weren't sure where.

Officer Mike Dunphy was doing a gun test fire when he was called back to the Capitol, and he remembers walking back with a sense of unease.

"People were running everywhere, and until the Air Force came overhead — that's when I felt safe," he said.

He wasn't sure what was going on, as it was nearly impossible to get much information out of the police radio system.

"Whenever something big happens, you don't try to get on the radio. You just get where you need [to be]," he said.

The department began organizing new checkpoints on the outer perimeter of the Capitol, so Dunphy waited to see where he would have to go next.

"The hierarchy was just figuring out what to do. They knew it was going to be a long-term thing, so they didn't want to rush to any one direction or another," he said.

This marked what Dunphy saw as a shift from preparations for their ratings and certification evaluations to "protection mode."

"The department has grown incredibly, and it's focused its attention more so to terrorist activity. So it's focused more on protection than anything else, and that is what they pay us for," he said.

Both Thompson and Dunphy stayed late that day, guarding the Capitol against a threat that hadn't yet completely taken shape. And both continued to come to work in the following weeks, serving long hours, working extra shifts, adjusting to the new normal.

"It never really occurred to me to say, 'Hey, I protected and served this day, but I think I'm done now.' That's not really the commitment I signed up for," Thompson said.